package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import javafx.scene.shape.Circle;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author lwk
 * @since 2025-6-1
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    @Autowired
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透方法
//         Shop shop = queryWithPassThrough( id);
        Shop shop =cacheClient
                .queryWithPassThrough( CACHE_SHOP_KEY, id, Shop.class, id1 -> getById(id1), CACHE_SHOP_TTL, TimeUnit.MINUTES);


        //用互斥锁解决缓存击穿
 //       Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿问题
//        Shop shop = queryWithLogicalExpire(id);

//         Shop shop = cacheClient
//                 .queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, id1 -> getById(id1), CACHE_SHOP_TTL, TimeUnit.SECONDS);
         if (shop == null) {
             return Result.fail("店铺不存在");
         }

         return Result.ok(shop);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);


    public Shop queryWithLogicalExpire(Long id){
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.如果为空直接返回
            return null;
        }
        //3命中需要判断过期时间
        //3.1把json反序列化对象
         RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop =JSONUtil .toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //3.2判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //3.3未过期
             return shop;
        }
        //4已过期,实现缓存重建
        //4.1获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //4.2判断是否获取成功
         if (isLock) {
             //4.3成功，开启独立线程，实现缓存重建
              CACHE_REBUILD_EXECUTOR.submit(() -> {
                  try {
                      //重建缓存
                      this.saveShop2Redis(id,20L);


                  } catch (Exception e) {
                      throw new RuntimeException(e);
                  }finally {
                      //释放锁
                      unLock(lockKey);
                  }
              });

         }
        //5返回过期的店铺信息
        return shop;
    }







    //缓存击穿互斥锁方法
     public Shop queryWithMutex(Long id){
         //1.从redis查询商铺缓存
         String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
         //2.判断是否存在
         if (StrUtil.isNotBlank(shopJson)) {//shopJson=""会不执行以下语句，所以下面要判断shopJson是否为空
             //3.存在直接返回
             Shop shop = JSONUtil.toBean(shopJson, Shop.class);
             return shop;
         }
         //判断查询到的redis是否为空值（查询到了，但是查询到的数据可能为空值）
         if (shopJson != null) {
             //返回错误结果
             return null;
         }
         //4.实现缓存重建
         //4。1获取互斥锁
         String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
         Shop shop = null;
         try {
             boolean isLock = tryLock(lockKey);
             //4.2判断是否获取成功
             if (!isLock) {
                 //4.3失败，进入休眠并重试
                 Thread.sleep( 50);
                return queryWithMutex(id);
             }

             //4.4成功，根据id查询数据库
             shop = getById(id);
             //4.5模拟重建延迟
              Thread.sleep(200);
             //5.不存在，返回错误
             if (shop == null) {
                 //将空值写入redis
                 stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,"" , CACHE_NULL_TTL, TimeUnit.MINUTES);
                 //返回错误信息
                 return null;
             }
             //6.存在，写入redis
             stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
         } catch (InterruptedException e) {
             throw new RuntimeException(e);
         }finally {
             //7.释放互斥锁
             unLock(lockKey);
         }
         //8.返回
         return shop;
     }


    //缓存穿透方法
     public Shop queryWithPassThrough(Long id){
         //1.从redis查询商铺缓存
         String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
         //2.判断是否存在
         if (StrUtil.isNotBlank(shopJson)) {//shopJson=""会不执行以下语句，所以下面要判断shopJson是否为空
             //3.存在直接返回
             Shop shop = JSONUtil.toBean(shopJson, Shop.class);
             return shop;
         }
         //判断查询到的redis是否为空值（查询到了，但是查询到的数据可能为空值）
         if (shopJson != null) {
             return null;
         }
         //4.不存在，查询数据库
         Shop shop = getById(id);
         if (shop == null) {
             //5.不存在，返回错误
             //将空值写入redis
             stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,"" , CACHE_NULL_TTL, TimeUnit.MINUTES);
             //返回错误信息
             return null;
         }
         //6.存在，写入redis
         stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
         //7.返回
         return shop;

     }

    //尝试获取锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return  BooleanUtil.isTrue(flag);
    }


    //存店铺信息和过期逻辑时间
    private void saveShop2Redis(long id,Long  expireSeconds) throws InterruptedException {
        //1.查询店铺数据
         Shop shop = getById(id);
         Thread.sleep(200);
        //2.封装成逻辑过期
         RedisData redisData = new RedisData();
         redisData.setData(shop);
         redisData.setExpireTime(LocalDateTime.now().plusMinutes(expireSeconds));
        //3.存入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }



    //释放锁
    private  void unLock(String key){
        stringRedisTemplate.delete(key);
    }
    @Override
    @Transactional
    public Result update(Shop shop) {
         Long id = shop.getId();
          if (id == null) {
               return Result.fail("店铺id不能为空");
          }
        //更新数据库
        updateById(shop);
        //删除缓存
         stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return null;
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo() // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }
}
